RE: [RFC PATCH v2 0/8] LIBVIRT: X86: TDX support
-----Original Message-----
From: Pavel Hrdina <phrdina(a)redhat.com>
Sent: Wednesday, July 21, 2021 10:23 PM
To: Duan, Zhenzhong <zhenzhong.duan(a)intel.com>
Cc: libvir-list(a)redhat.com; pkrempa(a)redhat.com; berrange(a)redhat.com;
Yamahata, Isaku <isaku.yamahata(a)intel.com>; Tian, Jun J
<jun.j.tian(a)intel.com>; Qiang, Chenyi <chenyi.qiang(a)intel.com>
Subject: Re: [RFC PATCH v2 0/8] LIBVIRT: X86: TDX support
On Fri, Jul 16, 2021 at 11:10:28AM +0800, Zhenzhong Duan wrote:
> Thanks Peter, Pavel and Daniel's comments on v1 version, now the v2
comes.
>
> * What's TDX?
> TDX stands for Trust Domain Extensions which isolates VMs from the
> virtual-machine manager (VMM)/hypervisor and any other software on the
> platform.
[...]
> * Misc
> Just let you know we have released v2 version of TDX qemu in [1], and
> the API for libvirt is keeping stable. Using these patches we have
> succesfully booted and tested a guest both with and without TDX enabled.
Overall looks good. It's missing documentation and the QEMU patches are
missing documentation as well. I was looking into Intel specification but I
failed to find the necessary info there as well.
What are the values `mrconfigid`, `mrowner`, `mrownerconfig` for, what data
is supposed to be stored there, what are the limitation and so on.
Oh, yes. Thanks
for point out. We will add the doc both for qemu and libvirt.
What I could gather these are exposed in the VM and are used for
measurement but that's it.
Another thing that I've missed in v1, QEMU patches are introducing new `-
machine pic=no` option and for TDX PIC has to be disabled. The libvirt
patches are putting it on the QEMU command line but it is not reflected in
the VM XML, so I would say we need to introduce new hypervisor feature [1]:
<features>
...
<pic state='on|off'/>
...
</features>
[1] <https://libvirt.org/formatdomain.html#hypervisor-features>
Will add this
feature.
> * Diff to v1:
> - give up using qmp cmd and check TDX directly on host for TDX capabilities.
> - use launchsecurity framework to support TDX
> - use <os>.<loader> for general loader
> - add auto firmware match feature for TDX
>
> A example TDVF fimware description file 70-edk2-x86_64-tdx.json:
> {
> "description": "UEFI firmware for x86_64, supporting Intel
TDX",
> "interface-types": [
> "uefi"
> ],
> "mapping": {
> "device": "generic",
I think using 'loader' as that's the actual device in QEMU used with this
firmware will be better. The patches posted to QEMU doesn't extend
`docs/interop/firmware.json` so this example may change once some specific
format is accepted by QEMU community.
Will do.
You will most likely need to add the firmware descriptor to QEMU project as
well (`pc-bios/descriptors/70-edk2-x86_64-tdx.json`). NOTE: The name
should not use `edk2` if it's not edk2 based firmware.
I see, will do. Thanks
very much for your suggestions.
Regards
Zhenzhong